In my VB.NET application, I'm trying to call a function from a 32-bit,
non-.NET dll file and I'm having problems. I believe I have the
correct signature for the dll with:

<System.Runtime.InteropServices.DllImportAttribute ("asdHTMLCompare.dll")>
_
Public Shared Function BuildCompositeFile(ByVal szOldFile As
System.IntPtr, _
ByVal szNewFile As System.IntPtr, _
ByVal szCompositeFile As System.IntPtr, _
ByVal szOldPrefix As System.IntPtr, _
ByVal szNewPrefix As System.IntPtr, _
ByVal szCompositePrefix As System.IntPtr, _
ByVal bCheckForChangedImages As System.Boolean) As System.Int32
End Function


I'm trying to call this function with the following code:

Dim html1 As System.String = "c:\test1.htm"
Dim html2 As System.String = "c:\test2.htm"
Dim composite As System.String = "c:\changes.htm"

Dim changes As System.Int32 = GlobalApp.BuildCompositeFile( _
System.Runtime.InteropServices.Marshal.ReadIntPtr( html1, 0), _
System.Runtime.InteropServices.Marshal.ReadIntPtr( html2, 0), _
System.Runtime.InteropServices.Marshal.ReadIntPtr( composite, 0), _
System.Runtime.InteropServices.Marshal.ReadIntPtr( ".htm", 0), _
System.Runtime.InteropServices.Marshal.ReadIntPtr( ".htm", 0), _
System.Runtime.InteropServices.Marshal.ReadIntPtr( ".htm", 0), _
True)

When I run this, I get the error:
An exception of type 'System.EntryPointNotFoundException' occurred in
ProductVision.Windows.Forms.dll but was not handled in user code.
Additional information: Unable to find an entry point named
'BuildCompositeFile' in DLL 'asdHTMLCompare.dll'.

What am I doing wrong?

Thanks in advance!
Dave

Am 08.06.2010 00:05, schrieb Dave Wurtz:
Maybe the function has a different name. You may want to use Dependency
Walker (<URL:http://www.dependencywalker.com/>) to examine the function
the DLL exports.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

On Jun 7, 5:16*pm, "Herfried K. Wagner [MVP]" <hirf-spam-me-
h... (AT) gmx (DOT) at> wrote:
Thanks for the reply.

As suggested, I downloaded the Dependency Walker program and opened
the DLL. In looking at the function I want to call and selecting
"Undecorate C++ Functions", this is what it shows:

int BuildCompositeFile(char *,char *,char *,char *,char *,char *,int)

Do I have the correct signature defined?

Thanks.
Dave

On Jun 8, 7:56*am, Dave Wurtz <dave_wu... (AT) asdsoftware (DOT) com> wrote:
Can anyone tell me if I have the correct signature defined here? Once
again, Dependency Walker showed the following for the function inside
the DLL that I am trying to call:

int BuildCompositeFile(char *,char *,char *,char *,char *,char *,int)

I have tried to create the equivalent signature in my VB.Net
application:


<System.Runtime.InteropServices.DllImportAttribute ("asdHTMLCompare.dll")>
_
Public Shared Function BuildCompositeFile(ByVal szOldFile As
String, _

ByVal szNewFile As String, _

ByVal szCompositeFile As String, _

ByVal szOldPrefix As String, _

ByVal szNewPrefix As String, _

ByVal szCompositePrefix As String, _

ByVal bCheckForChangedImages As Integer) As Integer
End Function

I must be doing something wrong because when I call the function, I
get the error:

An exception of type 'System.EntryPointNotFoundException' occurred in
ProductVision.Windows.Forms.dll but was not handled in user code.
Additional information: Unable to find an entry point named
'BuildCompositeFile' in DLL 'asdHTMLCompare.dll'.

Can someone help me with this please.

Thanks in advance!
Dave

Am 17.06.2010 22:57, schrieb Dave Wurtz:
Try it with
Declare Function...
with same name and same types.

Also try
Declare Ansi Function...

--
Armin

Dave Wurtz formulated the question :
If the dll is exposing a decorated name, then you must alias the vb
declare to the decorated name....

--
Tom Shelton

On Jun 17, 11:25*pm, Armin Zingler <az.nos... (AT) freenet (DOT) de> wrote:
Thanks for the suggestion. Unfortunately, I get the same error
message. This is how I typed it:

Public Declare Function BuildCompositeFile Lib
"asdHTMLCompare.dll" (ByVal szOldFile As System.String, _
ByVal szNewFile As System.String, _
ByVal szCompositeFile As System.String, _
ByVal szOldPrefix As System.String, _
ByVal szNewPrefix As System.String, _
ByVal szCompositePrefix As System.String, _
ByVal bCheckForChangedImages As Integer) As Integer

I also tried Public Declare Ansi/Auto/Unicode Function .... and all of
them throw the same exception:

An exception of type 'System.EntryPointNotFoundException' occurred in
ProductVision.Windows.Forms.dll but was not handled in user code
Additional information: Unable to find an entry point named
'BuildCompositeFile' in DLL 'asdHTMLCompare.dll'.

Any other suggestions?

Thanks.
Dave

On Jun 18, 8:47*am, Tom Shelton <tom_shel... (AT) comcast (DOT) invalid> wrote:
I don't understand what you are saying. Can you expand on this and/or
show an example?

Thanks.
Dave

Dave Wurtz submitted this idea :
By default a dll compiled in C++ will mangle the names - this is to
allow overriding of functions. So, your function BuildCompositeFile
maybe exported as something like ?BuildCompositFile@@YXZ. That isn't
probably the actual name - I the way names are mangaled or decorated
has alot to do with the compiler, and the types being passed. But the
point is, the entery point in the dll is probably NOT
BuildCompositeFile.

You can use dumpbin /exports on your dll to see the actual name table.
So, say the name is as above, then you would need to add an alias to
your VB declare:

Declare Ansi Function BuildCompositFile Lib "asdHtmlCompare.dll" Alias
"?BuildCompositFile@@YXZ" (.....)

HTH

--
Tom Shelton

Am 18.06.2010 20:03, schrieb Dave Wurtz:
Use the name you see prior to choosing to undecorate the function.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>